Brake



March 23, 1937. H K JR 2,074,730

BRAKE Filed Aug. 31, 1933 5 Sheets-Sheeh l W 237 H, H, KERR, JR

zwmvw BRAKE Filed Aug. 51, 1933 5 Sheets-Sheet 2 INVENTOR. Henry H. Kerr we @w A TTORNEY.

March 23, 1937. H. H. KERR, JR 2,074,730

BRAKE Filed Aug. 51, 1953 5 Sheets-Sheet 3 t" M i i A TTORNEYI March 23, 1937. H, H. KERR, JR

BRAKE Filed Aug. 31, 1935 l; IIIIIIIMIIJVIIIIIIIIVI 5 Sheets-Sheet 4 INVENTOR.

Hen y H Kerr A TTORNEX March 23, 1937. H.H. KERR, JR 2,074,730

BRAKE Filed Aug. :51, 1935 5 Shets-Sheet 5 /763 'INVENTOR. I757 [77 flemy H. Kerr A TTORNEY Patented Mar. 23, 1937 2,074,730 I alpine Henry H. Kerr, Jan,

Bendix Aviation South Bend, Ind, assignor to Corporation, South Bend, Ind,

a corporation of Delaware Application Augustin, 1933, Serial No. M73571 15 Claims.

This invention relates to aircraft and more particularly to means for controlling airplanes.-

Heretofore, airplanes have been provided with control surfaces including rudders, wheels and wheel brakes, and rudder bars and pedals for controlling the rudders and wheel brakes.

One of the objects of this invention is to provide, in combination with the above elements, a single means for applying all of the wheel brakes substantially equally, when desired, and additional means for transmitting a greater applying force, when desired, to one of the brakes than is transmitted to another of the brakes.

A further object is the provision of compressed air power to operate either of two brakes independently of each other the applying force being transmitted hydraulically from the cabin to the wheels.

A further object is the provision of means for O applying airplane brakes conjunctively with differential control of the brakes through the rudder pedals.

A feature 01 the illustration of the invention disclosed herein is the inclusion in combination of a hand lever, a hydraulic pressure creating device operated by the hand lever to apply the brakes equally, and means for upsetting this equalization by means of rudder pedals or by a rudder bar. A further feature of the invention is the provision of a fluid or mechanical by-pass which, when the hand lever is in the brake-oil position, permits easy and quick actuation of should be apparent after reading the subjoined specification and claims and after consideration of the accompanying drawings, in which:

Figure 1 is a fragmentary plan view of an airplane equipped wlth controls constructed accord- "ing to my invention;

Figure 2 is an enlarged diagrammatic plan view of a. portion of the structure shown in Figure 1;

Figure 3 is a diagrammatic view in side elevation of the structure shown in Figure 2;

Figure 4 is an enlarged view in vertical section of one of the power assemblies, including a master cylinder, a power cylinder and an air control valve;

Figure 5 is a perspective view of a portion of the airplane shown in Figure 1; c

Figure 6 is a plan view partly in section of a modified form of brake control;

Figure 7 is a view similar to Figure 6 showing a slightly different construction; 4

Figure 8 is another-view similar to Figure 6 and the rudder. Further objects and features of the invention curved lever positioned showing another slightly different form of construction;

Figure 9 is a plan view with parts in horizontal section showing a diilerent embodiment;

Figure 10 is a view similar to Figure 9 showing a 5 still difierent embodiment;

Figure 11 is a similar view showing another embodiment; and

Figure 12 is a similar view showing still another embodiment of my invention.

In Figures 1 to 5 inclusive I have shown an airplane provided with a fuselage Ill, supporting airfoils i2 and It, a rudder it and wheels l8 and 20. The rudder it is controlled by cables 22 and 24, which are adapted to be operated by foot ped- 15 als 26, 28, 3t and 32. The wheels l8 and are equipped with brakes 3t and 36, which are operated by hydraulic'motors 3t and 40. Liquid under pressure is supplied to the motors 38 and 40 through conduits such as M by means of master 20 cylinders 4t and 46. The master cylinders M and 46 are adapted to be operated either by a hand lever 48 or by auxiliary pedals 50, 52, 54, and 56, which are rotatively mounted on pedals 26, 2t, 3t, and 32 respectively.

The hand lever 48 operates the master cylinders M and 46 so as to supply liquid under substantially equal pressure to both of the brake cylinders 38 and til. The lever dB is secured to a torque shaft 58 and movement thereof rotates the shaft. The shaft carries an upstanding lever til, which is connected through a link 62 with an equalizing bar 66. The equalizing bar is connected through links 66 and 68 with levers 10 and M respectively.

The levers l0 and H (see Figure 4) and the interior of master cylinders 44 and 46 are substantially alike and one description will sufiice for both. It may be noted that the lever 10 is a chiefly within the casting forming the power cylinder 12, the lever being pivoted in the lower part of the casting at 76. The lever H is similarly postioned in a power cylinder 13. Within the master cylinder 46 there is provided a master cylinder piston 18 having formed therewith a rearwardly extending sleeve 80 against which an annular projection on the lever 10 bears.

Power means are provided to operate each master cylinder piston individually. Extending into the sleeve and rearwardly through the lever 10 is a. piston rod 82. The rear end of the piston rod 32 is secured to an air piston 84, which is thus also adapted to actuate the piston 18 as wen as the lever 10. 'Ihe rear end of the power cylinder 12 is connected to the valve 14 by rneans of an inlet port 86, and similarly the rear end of the power cylinder 13 is connected to a valve 15,

which is in all respects like the valve 14.

v The valve 14 controls the inlet of compressed 5 air to the power cylinder. It is provided with three chambers designated 14%, 14b, and 140 respectively, 14b being connected to the power cylinder by the port 86.. Chambers 14a and 14b are adapted at times to be connected and at other times to be closed from each other by means of the valve piston 88. Chambers 142; and "care adapted at times to be connected and at other times to be separated" by a flap. valve 90. The chamber 14a is connected to the at- ,mosphere through a port 92 and the chamber 140 is connected to a source of air under pressure through a port 94 and a conduit 95. A plunger 96, extending through the upper part of the valve 14, has a head 98 which bears upon a relatively strong spring I00 and through the spring is adapted to exert force upon a plunger I02. When the plunger I02 is moved downward it contacts with the valve piston 88 and through said valve .piston 88 is adapted. to move the flap valve 90 from its seat.

The valves 14 and 15 are controlled by the auxiliary pedals 50, 52, 54, and 56. The plunger 96 and the corresponding plunger for valve 15 are operated through levers I08 and H0 respectively.

Lever I08 is connected through a link II2 with a lever II4 secured to the shaft II6. Similarly, the lever IIO has secured thereto a link II8 connected to a lever I20 secured to the shaft I22.

The mechanism by whichthe shafts H6 and I22 are rotated by their associated auxiliary pedals 50, 52, 54, and56 includes a series of levers and connected links. The pedals 28 and 32 are secured to a tubular shaft I24 and the pedals 26 and 30 are secured to an inner concentric shaft I25. Movement of the pedals rotates the respective shafts, and inasmuch as the cables 22 and 24 are connected to levers on the ends of the respective shafts movement of the pedals thus actuates the rudder I6 through the cables 22 and pair of levers I26 and similarly mounted on the shaft I25 are a pair of levers I21. The ends of these levers I26 and I21 are connected through links I28 with levers I30 secured on shafts I32 to which there is also secured the associated auxiliary pedal. Thus rotation of. the auxiliary pedals also turns the levers I26 and I21. Also connected to the levers I26 and I21 are links such as I34 and I35 which have their opposite ends connected to levers suchas I36 and I31 secured to the shafts H6 and I22. Thus it is clear that rotation of the mainpedals with the shafts I24 and I25 without relative displacement of the auxiliary pedals has no effect upon the valves 14 or 15, and therefore has no efiect upon the brakes. Furthermora relative displacement of the auxiliary 'pedals will apply the brakes regardless of the position of the main pedals.

In the operation of the control system above as described, the pilot may be seated either in the right-hand side or the left-hand side of the cockpit. The operation is the same from either side.

Assuming that he is seated in the right-hand side of the cockpit, movement of the pedals 28 and Has a whole without relative displacementof the auxiliary pedals will rotate the rudder I6-through the cables 22 and 24. If the pilot desires to apply both brakes simultaneously, he may use either the hand lever 48 or the pedals 50 and 52, or he may take up slack with the hand lever and Mounted for rotation on the shaft I24 are a graduate the application by the pedals 50 and 52. Assuming that he desires to use the pedals only, he moves the auxiliary pedals 50 and 52 relative to the main pedals :26 and 28 and thus rotates the shafts I32 and through the levers I30, the links I28, the levers I26 and I21, the links I34 and I35, and the levers I36 and I31 rotates the shafts H6 and I22. This rotation acts through the levers H4 and I20, thelinks H8 and H2 and the levers I08 and H0 to operate the plungers in the valves 14 and 15 to move the pistons I02 downward and to move the lower-ends thereof into contact with the valve pistons or members 88. This closes off the chamber 14b from the atmospheric pressure in Ha. Further movement of the plunger unseats the valve so that air under pressure flows from the chamber 1 4c to the chamber 14b. Air under pressure passing through the port 86 forces the piston 84 to the right as seen in Figure 4 and thus moves the piston 18 to compress the liquid in the master cylinder 46 and to force it out under pressure.

' At the same time the piston in the master cylinder 44 similarly acts on the liquid therein. S0 liquid is forced out through both of the conduits 42 to the brake cylinders 38 and 40, thus applying the brakes 34 and 86.

Should the pilot desire to apply the brakes unequally he may use the pedals alone or first take up the slack with the hand lever and then graduate and differentiate the application by means of the pedals. Whether or not he uses the hand lever, he may actuate either one of the brakes separately to any desired extent by pressing upon the corresponding pedal.

Should he desire to apply both brakes equally andto maintain them applied, as for example when it. is desired to anchor the airplane at one place on the field, he may operate the brakes by the lever 48 alone. In operation of the brakes by the hand lever, whether merely for the purpose of taking up slack or as. a sole operating and anchoring means, the pilot pulls the lever 48. This action through the shaft 58, the lever 60,'t he link 62, the equalizing bar 64 and the links 66 and '68 operates the levers 10 and H to force the pistons 18 to the right through the sleeves 80. It is to be noted that the piston 18 may move to the right (in Figure 4) away from the piston rod 82 without moving the air piston 84. Moreover, operation of the pistons 18 by means of the air'pistons 84 does not affect the hand lever 48 and its associated linkage on account of the slot and pin connections at the inner end of'links 66 and 68.

In the structure shown in Figure 6 the rudder bar 221 is connected through cables 222 and 224 with the rudder. It is connected through links 2I2 and 2I8 withpistons 218 and,219 positioned in the cylinders 246 and 244 respectively. The forward ends of the cylinders.244 and 246 are enlarged and provided with relatively large pistons 339 and 34I. The pistons 339 and 34I are adapted to be operated by toggles 343 and 345 connected by a link 341 and both connected through said link to a cable 349 which leads to a hand operated lever (not shown). The cylinder 244 is adapted to supply liquid under pressure to one brake through a conduit 242, and the cylinder 246 is adapted to supply liquid'under pressure to another brake through a conduit 243. 'A reservoir '35I providing a reserve supply of liquid is connected with the cylinders 244 and 246 by means of bores 353, 355, 351,- and 359.

In the operation of this system rotation of the rudder bar 221 is adapted to operate the rudder by means of cables 222 and 224. Inasmuch as the links 2I2 and 2I8 are connected ,on opposite sides of the fulcrum of the rudder bar, the piston 5 218 is advanced-or retracted anamount equal to the retraction or advancement of piston 219.

Provided the pistons 339 and MI have not been moved from their normal positions shown, the

liquid may flow freely throughthe bore 351 from one cylinder to the other so that there is no unnecessary eifort in moving the rudder due to the operation of the brakes. is desired to apply the brakes, a pull upon the cable 349 through the hand lever moves the pisl5.tons 339 and BM to develop equal pressure in both'of the brake motors and apply both of the brakes. At the same time the movement of the pistons 339 and 34I cuts off communication through the bore 351. Thereafter rotation of the rudder bar 221 upsets the equalization between the two cylinders and enables the operator to apply one brake with greater force than the other as desired. Inasmuch as this upsetting operation is accomplished by the rudder bar, it

2 is natural for the pilot to steer by means of the brakes.

In Figure 7 the rudder bar 421 is connected through the cables 422 and 424 with the rudder and through the links M2 and M8 with the pistons 418 and 419m the cylinders 444 and 446. The cylinders 444 and 449 are formed integrally and are mounted to slide upon a frame which includes rods 59I and 563. A toggle 543 is connected at one end .to a portion of the frame 5 and at the opposite end to the casting which forms the cylinders 444 and 446. The knee of the toggle is connected to a cable 549 which leads to the hand lever (not shown). The transverse bores 555 and'559 are connected by a lon- ,gitudinal bore 553 to a reserve-supply of fluid (not shown). The cylinders 444 and 446 are connected by conduits 442 and 443 with the brakes.

The operation of this form of my device is 5 substantially the same as that shown in Figure 6. However, in applying the brakes equally the whole unit including the cylinders 444 and 446 moves while the pistons 418 and 419 remain stationary, thus eliminating the necessity for auxiliary pistons such as 339 and 34I.

In the device shown in Figure 8, a rudder bar 621 is'connecte'd through tensionelements' 622 and 624 with a rudder and through the compression. elements 6 and 9I8 with pistons 618 and 619. The piston 618 is positioned in a cylinder 646 which is connected through a conduit 643 with one of the brakes, while the piston 619 is positioned in a cylinder 944 which is connected through a conduit 642- with the other brake. Surrounding the piston 619 in the cylinder 644 is an annular piston HI, and surrounding the piston 619, in the cylinder 646 is an annular piston 639. A yoke 141 having bifurcated ends is adapted to bearupon the outer ends of the annular pistons 139 and 14! and is secured to one end of a rod 149. The opposite end of the rod 149 is connected in any suitable manner witha hand lever (not shown) 7 The operation of this form of my invention is substantially the 'samejas that shown in Figures 6 and '1. However, the equal application of the brakes and the closing of the by-pass between the two cylinders, as well as the initial operation of the brakes, is pistons139'and 14I However, if it.

accomplished by the annular In the embodiment shown in Figure 9, the rudder bar 821 is connected to the rudder through tension members 822 and 824 and to pistons 818 and 819 through compression elements 9I2 and 8I8. The pistons 818 and 819 are contained in 5 cylinders 844 and 846 which have conduits 842 and 843 leading to the brake motors. The cylinders 844 and 846 are normally connected to each other through auxiliary cylinders 969 and conduit 842 being connected to auxiliary 0 cylinder 969 by a conduit 965, and conduit 843 being connected to'auxiliary cylinder 9" by a conduit 961. The cylinders 969 and 911 are connected to each other by means of a transverse bore 951 which leads into a main bore 15 954, the latter being connected through a conduit 952 with a reservoir for the supply of additional fluid. Positioned in the cylinders 969 and 91I are pistons MI and 939 which are adapted at times to close the transverse bore 951 and 20 thus cut off communication between the cylinders 969 and 9H and thus between the cylinders 944 and 946. Moreover, actuation of the pistons 939 and 94i is adapted to supply initial braking pressure for operating the brakes, the pressure developed thereby being substantially equalized. The pistons 939 and '94I are adapted to be operated by toggles 943 and 945 which are connected by a link 941 which is also connected to atension element 949, the latter leading to a hand lever (not shown).

The operation of the above described embodiment will be apparent from the description when considered in connection with the operation of the'previous embodiments, the structure being substantially the same as that shown in Figure 6, except that separate cylinders are provided instead of combining the main cylinder and the auxiliary cylinder in one unit.

In Figure 10 the rudder bar I921 is connected 40 through the cables I922 and I924 with the rudder and through the compression rods NH and I9I8 with the pistons I919 and I919. The con-. duits I942 and I943 pass through a valve block M11. The valve block II11isprovided with bores 5 H19 and H81 and with a by-pass I I8I having a portion thereof formed in a ,plug valve II83.

.The plug valve M83 is adapted to be rotated to .with the toggle H45. Conduits H85 and H96 connect'the bores H19 and H81 with the brakes. Additional liquid is supplied, when needed, .to the cylinders I944 and I946 through a conduit 60 II and bores I953 and I955, and to cylinder II69 through conduit H52 and bores II51, H54 and H59.

In the operation of this embodiment of my invention, movement of the hand lever closes the Q5 by-pass I I 8| and forces fluid under pressure from the cylinder 69. This accomplishes the initial equal application of the brakes. Subsequent upsetting of the braking may be accomplished by rotation of the rudder bar, thus operating the 70 pistons I918 and I919 to force fluid selectively from one of the cylinders I944 and I946.

In the embodiment shown in Figure 11, the rudder bar I221 is connected to the rudder through cables I222 and I224 and to a lever I389 75 I385 and I386 leading to the associated brakes,

and atransverse bore I38I connects the'bores I319 and I381. A plug valve I383 is adapted to open or close the by-pass formed by the bore I38I, the plug valve being adapted to be operated by a lever I391 connected by a lost motion connection with a toggle I345. The knee of the toggle is connected to a tension member I349 which leads to the hand lever and is also connected by a link I341 with another toggle I343. The conduit I365 leads to a cylinder I369 which is provided with a piston I34I connected 1 to the toggle I343. Additional liquid is supplied when needed by' a conduit I352 and bores I351, I354 and I359.

By operating the hand lever the piston I3 is operated to take up the slack at the brakes and, if desired, apply the brakes equally. In this action the floating piston I219 is moved to the right (as seen in Figure 11) the liquid flowing freely through the by-pass I38I. Towards the end of the movement of the hand lever the by-pass I38I is closed and the brakes on each side may thereafter be separately varied by movement of the piston I218 by means of the rudder I221.

It is to' be noted that in the structures-shown in Figures 6, 8, 9, 10, and 11, movement of the rudder bars is normally not hindered .by the hydraulic system du to the by-passes 351, 151, 951, BI, and I38I.

In Figure 12 the rudder bar is formed in two sections I421 and I428 resiliently held together so that normally they act as a unit. The section I421 is connected through the link I4I2 with the piston I418 in cylinder I444 and the section I428 is connected by link I4I8 with piston I419 in cylinder I446. The cylinder I444 is connected by conduit I443 with brake wheel motor I438'and with rudder motor I595, which together with rudder motor I593 controls rudder I4I6. The cylinder I446 is connected by conduit I442 with brake wheel motor I449 and with valve block I511. The valve block is formed with communieating bores-I519, I58I-, and I581. The former is connected to the conduit I442 and the latter with a conduit I59I which is connected at its other end with the rudder motor I593. The cylinders I444 and I446 are formed with intercommunicating bores I515 and I513, the latter of which is connected by a conduit I565 with an auxiliary pressure cylinder I569. The cylinder I569 is provided with a piston I54I- which is operated through a toggle I543 by a tension elemerit I549 connected to a hand lever (not shown) A link I541 connected to the knee of the toggle is fastened at its opposite end to a lever I545 controlling the valve plug I583. The cylinders I444 and I446- are supplied with additional liquid when required by a conduit I45I through bores I453 and I455.

When the pilot desires to actuate. the rudder without actuation of the wheel brakes, the hand lever is left in its normal position, thus maintaining the valve 1583 open as shown and the piston I54I in the position shown. Rotation of the rudder bar formed by the sections I421 and I428 operates the rudder motors I593 and but does not affect the motors. I438 and If it is desired to apply the brakes equally, this may be accomplished either by use of the hand lever alone, thus applying pressure to both sides of the system through the conduit I565 by means of the piston I54I, or by means of pressure on both sections I421'and I428, thus moving both pistons I418 and I419 forward in their cylinders. If it is desired to apply the brakes unequally, the hand lever is first operated to close the valve I583. Thereafter, operation of the rudder bar I421-I428 is effective to apply greater pressure to one of the motors I438 and I440 than to the other.

It is to be understood that the above'described embodiments of my invention are for the purpose of illustration only and various changes may be made therein without departing from the spirit and scope of the invention.

I claim:

1. In an airplane control system for an airplane equipped with a right wheel and a left wheel and with a rudder, in combination a hydraulic motor for each brake, a pair of hydraulic motors for the rudder, each of which is arranged to move the rudder in a direction opposite'to the other, a pair of master cylinders one connected to one of said brake motors and to one of said rudder motors and the other connected to the other brake motor and the other rudder motor, and means for varying pressures in said master cylinders simultaneously either by increasing the pressure in both or by increasing the pressure'in one and decreasing the pressure in the other, said means comprising a two piece rudder bar and a pair of pistons one positioned in one cylinder and connected to one piece of the rudder bar and the other positioned in the other cylinder. and connected to the other piece of the rudder bar.

2. In an airplane control system for an airplane equipped with a right wheel and a left wheel and with a rudder, in combination a hydraulic motor for each brake, a pair of hydraulic motors for the rudder, each of which is arranged to move the rudder in a direction opposite to the other, a pair of master cylinders one connected to one of said brake motors and to one of said rudder motors and the other connected to'the other brake motor and the other rudder motor, a master cylinder piston in each master cylinder, and means for actuating said master cylinder pistons simultaneously either in opposite directions or in the same direction, said means comprising a pair of levers connected respectively to said pistons and arranged normally to move in the same rotative direction but capable of moving in opposite directions.

3. In an airplane control system for an airplane equipped with a right wheel and a left til . closing the connection from one r to the other brake inders, means for actuating said master cylinder pistons simultaneously either in opposite directions or in the same direction, and a valve for of said cylinders to its associated rudder motor.

4. In an airplane control system for an airplane equipped with a right wheel and a left wheel and with a rudder, in combination a hydraulic motor for each brake, a pair of hydraulic motors 'for the rudder, each of which is arranged to move the rudder in a direction opposite to the other, a pair of nected to one of said brake motors and to one of said rudder motors and'the other connected motor and the other rudder motor, pistons in said master cylinders, means for actuating said master cylinder pistons simultaneously either in opposite directions or in the same direction, an auxiliary cylinder, a piston therein, a hand lever for controlling said auxiliary piston, a connection from said auxiliary cylinder to both of said first mentioned cylinders, a valve for closing the connection between one of said first mentioned cylinders and its associated rudder motor, and common means connecting said hand lever to said auxiliary piston and said valve.

5. In an airplane control system for an airplane equipped with a right wheel and a left wheel and with a rudder, in combination a hydraulic motor for each brake, a spring for each brake motor which normally prevents it from being actuated, a pair of hydraulic motors for the rudder, each of which is arranged to move the rudder in a direction opposite to the other,

a pair of master cylinders one connected to one of said brake motors and to one of said rudder motors and the other connected to the other brake motor and the other rudder motor, a piston in each of said master cylinders, and means for actuating said master cylinder pistons simultaneously either in opposite directions or in the same direction.

6. In a hydraulic pressure creating devicefor airplane brakes for an airplane, incombination means for developing hydraulic pressure comprising a, pair of master cylinders, and a pair of pistons in said cylinders, a by-pass connecting said cylinders, connections for operating said pistons in opposite directions, separate means for developing substantially equal increased pressures in said cylinders, and means actuated by or more of said pressure dev'eloping means for controlling said bypass.

7. In a hydraulic pressure creating device for airplane brakes for an airplane, in combination apair of master cylinders, a pair of pistons in said cylinders, connections for operating said pistons in opposite directions, means for developing increased pressures in said cylinders, means for equalizing the pressure in said cylinders including a passage, a valve for closing said passage, and means actuated by the operation of said increased pressure developing means for opening and closing said valve.

8. In a hydraulic pressure creating device for airplane brakes for an airplane, in combination a pair of master cylinders, a pair of pistons in said cylinders, connections for operating said pistons in opposite directions, and separate means for developing increased pressures in said cylinders, means for equalizing pressures in said cylinders, including a fiuid passage, a valve for closing said fluid passag and a common control master cylinders one con-- for said pressure developing means and said valve.

9. In an airplane control system for an airplane equipped with a right wheel and a left wheel with a brake for each wheel, and with a control surface, in combination a hydraulic motor for each brake, a pair of' hydraulic motors for said control surface, each of which is arranged to move said control surface in a direction opposite to the other, a pair of master cylinders one connected to one of said brake motors and to one of said control surface motors and the other connected to the other brake motor and the other control surface motor, a master cylinder piston in each master cylinder, and means for actuating said master cylinder, pistons simultaneously either in opposite directions or in the same direction.

'10. In an airplane control system for an airplane equipped with a right Wheel and a left wheel with a, brakefor each wheel and with a control surface, in combination a hydraulic motor for each brake, a pair of hydraulic motors for the control surface, each of which is arranged to move said control surface in a direction opposite to the other, a pair of master cylinders one connected to one of said brake motors and to one of said control surface motors and the other connected to the other brake motor and the other control surface motor, a piston in each of sad master cylinders, means for actuating said master cylinder pistons simultaneously either in opposite directions or in the same direction, an auxiliary cylinder, 9, piston therein, a hand lever for controlling said auxiliary piston, and a connection from said auxiliary cylinder to both of said first mentioned cylinders.

11. In a control system for an airplane a pair of separate means for retarding the movement of the airplane when it is upon the earth; control mechanism for said retarding means comprising a lever and a control means; hydraulic force transmitting means connecting a portion of said control mechanism and said retarding means and including a motor cylinder for each retarding means, a hydraulic pressure creating device operably connected to said lever, hydraulic connections between said pressure creating device and both of said motor cylinders; means including a fluid passage for equalizing the pressures beone of said motor and means for closing said fluid pas- .sageoperated by the initial movement of one of said hydraulic pressure creating means.

12. A control system for an airplane; a pair of separate wheel brakes for retarding the movement of the airplane when it is upon the earth; control mechanism for said brakes comprising a lever and a control means; hydraulic force transmitting means connecting a portion of said control mechanism and said brakes and including a motor cylinder for each brake, a hydraulic pressure creating device operably connected to said lever, hydraulic connections between said pressure creating device and both of said motor cylinders; means including a fluid passage for equalizingthe pressures between said motor cylinders; and means for upsetting the equalization of pressure and for operating one of said brakes with ment of one of said hydraulic pressure creating.

means. i

13. A control system for an airplane; a pair of separate means for retarding the movement of the airplane when it is upon the earth; control mechanism for said retarding means comprising a lever and a control means; hydraulic force,

5 transmitting means connecting a portion of said control mechanism and said retarding means and including a motor cylinder for each retarding means, a hydraulic pressure creating device operably connected to said lever, hydraulic connections between said pressure creating device and both of said motor cylinders; means including a fluid passage for equalizing the pressures between said motor cylinders, and means for upsetting the equalization of pressure and for operating one of said retarding means with greater force than the other, said upsetting means comprising said control means, an additional pair of separate hydraulic pressure creating means both included in said hydraulic force 30 transmitting means and each connected to one of said motor cylinders, and means for closing said fluid passage operated by' the initial movement of one of said pair of additional hydraulic pressure creating means.

14. A control system for an airplane; a pair of separate means for retarding the movement of the airplanewhenjt is upon the earth; control mechanism for said retarding means comprising a lever and a control means; hydraulic 40 force transmitting means conecting a portion of said control mechanism and said retarding means and including a motor cylinder for each retarding means, a hydraulic pressure creating device operably connected to said lever, hydraulic connections between said pressure creating device and bothof-said motor cylinders including a fluid.

to one of said motor cylinders, and means for 7 closing said fluid passage operated by the initial movement of one of said hydraulic pressure creating means.

15. A control system for an airplane; a pair of separate means for retarding the movement'of the airplane when it is upon the earth; control mechanism for said retarding means comprisinga lever and a control means; hydraulic force transmitting means connecting a portion of said control mechanism and said retarding means and including a motor cylinder for each retarding means, a hydraulic pressure creating device operably connected to said lever, hydraulic connections between said pressure creating device and both of said motor cylinders including a fluid passage; and means for upsetting the equalization of pressure and for operating one of said retarding means with greater force than the other; said upsetting means comprising said control means, an additional pair of separate hydraulic pressure creating means both included in said force transmitting means and each connected to one of said motor cylinders, and means for closing said fluid passage operated by the initial movement of one of said pair of additional hydraulic pressure creating means.

HENRY H. KERR, JR. 

